The need for portable units for pressurizing various objects is well known. Such devices run the gamut from the simple rigid hand operated bicycle pump type or flexible bellows-type foot operated compressor unit to small electric compressors that plug into the cigarette lighter socket of a vehicle to more sophisticated electric units like the one disclosed by U.S. Design Pat. No. 301,887 "Air Compressor or Similar Article" to Price et al.
However, while beach balls and tires always need to be inflated, and dispensing units such as flit-type guns must be continuously re-pressurized to work, there is another whole field of things that need pressurizing to be used: aerosol dispensing containers.
Most aerosol containers now on the market, regardless of whether they dispense hair spray or insect repellent, are pressurized at the point of filling by the addition of some sort of propellant gas, frequently propane or butane. (Chlorofluorocarbons were used in the past but they have been illegal for such use in the U.S. since 1978). Methods of pressurizing such containers without the need for chemical propellant additions are desirable for a variety of environmental, safety and economic reasons.
Currently available pressurized aerosol dispensing containers are single-use items that are not reusable or even easily recyclable.
Further, currently available pressurized aerosol dispensing containers need to comply with the U.S. Department of Transportation regulations governing the shipment of pressurized containers from the point of filling to the point of sale or use. While compliance with such regulations is a necessary safety precaution when pressurized containers are being shipped, such compliance adds complexity and cost to shipping. The containers of the present invention, whether of the single fill or refillable variety, can be shipped unpressurized and pressurized for use only by the actual user of the product contained in the container.
One approach to solving these problems is that provided by the Eurospray.TM. container marketed in the U.S. by LD Systems of Charlotte, N. C. This container is an operationally pressurizable plastic container having a built in pressure safety valve that can be refilled. Air is pumped into the unit by a pump which is an integral part of the container. While such a unit has many virtues, it does require the user to expend time and energy repressurizing the container, a fact that becomes significant in situations of either heavy use of the dispensing unit or for end users for who either the time factor or the required physical effort are concerns.
A refillable and pressurizable airless sprayer is disclosed by U.S. Pat. Nos. 4,197,884 and 4,093,123, both to Maran, "Airless Sprayer and Pressurizing System". These patents disclose a container with a moveable piston. The liquid to be dispensed is contained in a chamber above the piston head. A second chamber, below the piston head, can be pressurized, through a valve in the container, by an air compressor.
U.S. Pat. No. 3,592,244 to Chamberlin, "Flask-Charging Apparatus" discloses a compressor unit designed to pressurize an air flask to a predetermined pressure. The compressor unit has a flask-receiving area containing a projecting tube that will fit into an opening in the back of the air flask. The air flask itself simply contains pressurized air. The product to be dispensed from the system is contained in a separate dispensing unit which is connected to the air flask.
PCT publication WO93/04928 to Kaeser, "Aerosol Can Pressurizing Device and Aerosol Can Therefore" discloses an air compressor having a receptacle having a non-return valve into which an aerosol can be placed for repressurizing, and means for coupling the air compressor and the aerosol can, and means for turning the air compressor off when pressure within the can reaches a predetermined level.